Vascular anchoring introducer sheath

ABSTRACT

Among other things, there is disclosed structure and methods for maintaining access to a location in the body while reducing or eliminating the potential for pulling an access device (e.g. a catheter) back through an opening. An introducer sheath includes a distal indented portion and a balloon, so that once placed in a desired location through tissue, the balloon can be inflated to anchor the sheath against retraction. In particular embodiments, structure and methods for accessing the pericardial cavity via the right atrial appendage are shown.

The present disclosure concerns devices for safely anchoring withrespect to tissue and allowing introduction of other devices into adesired treatment location through them. In particular, the disclosureconcerns an introducer able to be inserted through and anchored withrespect to tissue such as the right atrial appendage. This applicationis a divisional of Ser. No. 16/394,182, filed Apr. 25, 2019 which is acontinuation of PCT/US2017/058245, filed Oct. 25, 2017 which claimspriority to U.S. Provisional Application Ser. No. 62/412,646, filed onOct. 25, 2016, which is incorporated herein by reference in itsentirety.

BACKGROUND

There are numerous applications in which a vascular introducer sheath ispassed through tissue and inadvertent pullback would be undesirable. Forexample, a common approach for accessing the left atrium of the heart isto enter the right atrium via the venous system and puncture through theinteratrial septum to reach the left atrium. Once across the septum, ifthe introducer inadvertently is pulled back across the septum into theright atrium, puncturing the septum must be repeated which causesadditional trauma. In another example, a way of accessing thepericardium from within the heart is by puncturing out of the rightatrial appendage into the pericardium. Inadvertently pulling theintroducer sheath back into the heart could cause pericardial tamponade,which can lead to death.

When accessing the vascular system via a percutaneous puncture, bleedingor a hematoma can occur if the introducer sheath is inadvertently pulledout of the blood vessel. When crossing from one blood vessel to anotherby exiting the bloodstream (e.g. from the vena cava to the aorta),bleeding or a hematoma can occur if the introducer sheath isinadvertently pulled out of the blood vessel.

Currently available devices do not have an anchoring featureparticularly suitable to the sensitive tissues of the heart. A number ofdevices have been proposed to access cardiac tissue or the pericardiumby punching or other insertion through cardiac or adjacent tissues. Suchdevices allow access, but commonly lack any structure for holding thedevice with respect to the tissue through which the device is placedbecause such anchoring is not required or desired. For an access devicethat allows medication or other fluid to flow into a cavity, as oneexample, an anchor is not required. An anchor is also undesirable for anintroducer where the opening or tissue through which the introducer isplaced is in a sensitive location, and where expansion or damage to thehole or tissue must be avoided.

The present disclosure provides a device that resolves such issues.

SUMMARY

Among other things, there is disclosed an introducer sheath forinsertion through the right atrial appendage into the pericardialcavity. Embodiments of the sheath can include an inner lubricious layerdefining an internal lumen extending along a longitudinal axis of thesheath from a proximal end to a distal end of the sheath, an outerheat-settable layer surrounding the inner layer and extending from theproximal end to the distal end, and a coil core fixed between the innerlayer and the outer layer. The coil core may extend through at leastpart of a proximal portion of the sheath and at least part of a medialcurved portion of the sheath but not into a linear distal portion of thesheath which includes the distal end in particular embodiments.

The linear distal portion may have a circumference around thelongitudinal axis, and include an indented portion around the entirecircumference, the indented portion having proximal and distal edges anouter diameter less than a maximum outer diameter of the linear distalportion. A balloon is in the indented portion, the balloon having adeflated condition in which the balloon does not extend past either ofthe edges or the maximum outer diameter of the linear distal portion,and an inflated condition in which the balloon extends coaxially pastthe maximum outer diameter of the linear distal portion around thecircumference of the linear distal portion. In the inflated condition,the balloon has a surface facing proximally that is angled with respectto the longitudinal axis at an angle between and including 60 to 90degrees.

In certain embodiments, the internal lumen has a constant inner diameterthrough the proximal, medial and distal portions of the sheath. Thesheath can also include at least one marker that abuts the proximal edgeof the indented portion, the marker being at least one of radiopaque andechogenic. In particular the marker may be proximal of a proximal-mostpart of the balloon. A fluid lumen extends to an opening in the indentedportion, whereby a fluid may be forced through to inflate the balloonand may be withdrawn to deflate the balloon. Particular embodiments usepolytetrafluoroethylene (PTFE) for the inner layer, and/or PEBAX for theouter layer. The outer layer may be heat-set to a desired shapefollowing attachment of the inner and outer layers to each other.

Methods, including methods of accessing a pericardial cavity of apatient via a right atrial appendage of the patient with an introducersheath, are also disclosed. Such methods can include inserting theintroducer sheath into the inferior vena cava of the patient, theintroducer sheath having a curved medial portion and a linear distalportion, the linear distal portion including an indented portion aroundthe entire circumference and a balloon in a deflated condition withinthe indented portion so that no part of the balloon extends beyond amaximum outer diameter of the linear distal portion or outside of theindented portion. The sheath can be moved to the right atrium of theheart of the patient to a position adjacent the right atrial appendage,and passed through the right atrial appendage to the pericardial cavityso that the indented portion is within the pericardial cavity. Theballoon can be inflated within the pericardial cavity, so that theinflating does not enlarge a hole through the right atrial appendagethrough which the sheath passes, and the inflated balloon can be engagedwith tissue of the right atrial appendage that faces the pericardialcavity.

In particular examples, the introducer sheath is an embodiment describedherein. The sheath may be imaged when it extends through the rightatrial appendage, and confirming that a marker abutting a proximal edgeof an indented or balloon section is beyond the tissue of the rightatrial appendage before performing the inflating step. A dilator may bewithin and extending from the sheath, and the passing step may includedilating a hole through the right atrial appendage with the dilator. Incertain embodiments, the dilator and sheath are placed and moved over awire of a wire guide, which has already been passed through the rightatrial appendage and into the pericardial cavity or space. The dilatormay have a very gradual taper to allow gentle dilation of the rightatrial appendage, such as a taper length of about 5 centimeters. Thedilator may also lock into or with respect to the sheath duringdelivery, so that the dilator and sheath move in unison during theinsertion procedure.

One or more devices may be passed through the sheath and into thepericardial cavity for use in a treatment procedure after the engagingstep, and while the balloon is inflated and engaged with tissue of theright atrial appendage. In particular examples, the device(s) mayinclude a belt for placement in the atrioventricular groove as atreatment for tricuspid valve regurgitation. The balloon may be deflatedso that the balloon collapses to a condition within the indented portionso that no part of the balloon extends beyond a maximum outer diameterof a distal portion of the sheath or outside of the indented portion ofthe sheath. Further, a disengaging can occur between the engaging andthe deflating, wherein the disengaging includes moving the sheath withrespect to the right atrial appendage to move the balloon away fromtissue of the right atrial appendage that faces the pericardial cavity.

The disclosed devices and methods prevent inadvertent pullback of anintroducer catheter within the bloodstream or cardiac tissues. Incertain embodiments, a tubular sheath has a balloon mounted along theexterior of its shaft, e.g. in an indented portion. The sheath is sizedfor introduction through the vascular system and placement at a desiredlocation in the body. It is also sized so that a medical device can bepassed through it to the desired location. In one example, theintroducer sheath is sized such that 14 French devices can pass throughit. At the proximal end is a port that communicates with the innerdiameter of the catheter. A second port on the proximal end is in fluidcommunication with the balloon, such that it can be used to inflate ordeflate the balloon. Fluid communication between the second port andballoon can be achieved either via a second lumen in the catheter(multi-lumen catheter system) or a sleeve which is placed around thesheath or inner lumen (coaxial system). More generally, devices formaintaining access after exiting a vascular or cardiac wall include acatheter or sheath having a distal end and an outer diameter, andfurther including a bonded balloon attached to the distal end, whereinthe balloon inflates to a diameter that is at least 2 times the diameterof the access catheter's outer diameter, and preferably at least 3times. Ports on the proximal end can be provided for device insertion,contrast injection, and/or balloon inflation while maintaining a seal toprevent blood loss out of the proximal end of the catheter or sheath.

Exemplary methods include passing a sheath from the inferior vena cavavia the right atrium to the right atrial appendage. The sheath is passedthrough the wall of the right atrial appendage such that the distal endof the sheath is in the pericardial cavity. The inflated balloon at thedistal end prevents the sheath from being pulled back into the heart.More generally, methods are disclosed for maintaining access afterexiting a vascular or cardiac wall through inflation of a balloon thatis attached to the access sheath or tube so that the balloon inflatesoutside of the wall to prevent premature pullback and subsequent loss ofaccess. In particular, methods for achieving and maintain pericardialaccess, so that devices and tools can be delivered inside thepericardium safely without losing access prematurely, are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side plan view of an embodiment of an introducer sheath asdisclosed herein

FIG. 2 is a cross-sectional view of the embodiment of FIG. 1, takenalong the lines II-II in FIG. 1.

FIG. 3 is a cross-sectional view of the embodiment of FIG. 1, takenalong the lines III-III in FIG. 1.

FIG. 4 is a side plan view of the embodiment of FIG. 1 in an inflatedcondition.

FIGS. 5-7 are side plan views of the embodiment of FIG. 1 in use.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

While the present disclosure may be embodied in many different forms,for the purpose of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the disclosure is thereby intended. Any alterations andfurther modifications in the described embodiments and any furtherapplications of the principles of the present disclosure as describedherein are contemplated as would normally occur to one skilled in theart to which the disclosure relates.

Referring now generally to the drawings, there is shown an embodiment ofan introducer sheath 20, which is adapted for use in the body to allowother devices (such as catheters, diagnostic devices, or treatmentdevices) to travel through sheath 20 to a desired location in the body.As an example, sheath 20 is preferably able to be inserted into thevasculature of a patient, such as into the inferior vena cava (IVC),moved to a location for diagnosis or treatment such as the heart, andanchored in or through tissue at or near the location. Another device,such as a dilator or treatment device, is passed through and out of adistal end of sheath 20, so that the device extends through the tissuewith respect to which sheath 20 is anchored.

Sheath 20 in the illustrated embodiment is a multi-layer device, havingan inner layer 22 surrounding a central lumen 24, an outer layer 26, anda coil core 28 that is between and/or at least partially embedded in oneor both of inner layer 22 and outer layer 26. Sheath 20 has a proximal(i.e. closer to the user or operator of sheath 20) portion 32, a medialcurved portion 34, and a distal (i.e. farther away from the user oroperator of sheath 20) portion 36.

Inner layer 22 in a particular embodiment is of a highly lubricioussubstance, for example PTFE (also known as Teflon), defining a lumen 24that is sized to permit passage of a dilator D to assist in placement ofsheath 20, as well as to permit passage of additional tools orstructures for treatment of tissue, as will be discussed further below.The diameter of lumen 24 is constant in the illustrated embodimentthrough proximal, medial and distal portions 32, 34, 36, and may be 9French, 11 French or 13 French as particular examples. The use of PTFEor similarly lubricious material for the inner layer is preferred so asto easily pass dilator D or other devices, even in an environment likethe body (e.g. the vasculature).

Outer layer 26 surrounds inner layer 22 to form an outermost surface 40in a particular embodiment is of a heat-settable and soft orlow-friction substance, for example PEBAX (polyether block amide). Outerlayer 26 may be heat-set into a desired shape, including cylindrical oroval, and is easily formed into the surfaces described below withrespect to distal portion 36. In particular embodiments, a cylindricalshape will make turning sheath 20 by application of torque easier, andin other embodiments an oval shape can make anchoring with respect totissue more secure. It will be understood that sheath 20 may have asingle outer shape or configuration, e.g. cylindrical throughout, or mayhave more than one outer shape or configuration, e.g. cylindrical inproximal and/or medial portions 32, 34, and oval in all or part ofdistal portion 36.

Coil core 28 is between and/or at least partially embedded in one orboth of layers 24, 26 in the illustrated embodiment. Core 28 is a coiledfilament or wire in a particular embodiment, of a sturdy material suchas biocompatible metals or plastics. Core 28 provides sturdiness tosheath 20 to allow torqueing for turning of sheath 20 around alongitudinal axis and resist or prevent kinking, while its windingsmaintain flexibility in sheath 20 so that it can be moved through thevasculature or other paths through the body. The filament or wire ofcore 28 may be cylindrical in cross section, or rectangular in crosssection (e.g. a flat wire, indicated in FIG. 3), and core 28 may includea single wound filament or wire, or two or more filaments or wires woundaround each other or around a common longitudinal axis. The illustratedembodiment shows coil core 28 partially embedded in both layers 22 and26, i.e. a part of the windings of core 28 is within the largest outerdiameter of inner layer 22 and beyond the smallest inner diameter ofouter layer 26. It will be understood that core 28 may be wound aroundthe outer diameter of inner layer 22, and the outer layer 26 molded orotherwise formed around core 28 and layer 22, so that core 28 isembedded at least partially in outer layer 26. Alternatively, core 28may remain between the outer diameter of inner layer 22 and the innerdiameter of outer layer 26, and not be embedded in either layer.

Proximal portion 32 of sheath 20 is generally straight in theillustrated embodiment, with sufficient flexibility to permitmaneuvering through the vasculature (e.g. through the IVC to the heart).Proximal portion 32 includes a portion of each of inner layer 22, outerlayer 26 and coil core 28. A proximal end 44 may include a hub orlocking mechanism 46 that engages with or locks to a handle or otherdevice to enable moving, turning or otherwise maneuvering sheath 20,either by itself or in conjunction with another related device. As aparticular example, dilator D may include a hub (not shown) that iscompatible with mechanism 46 of sheath 20, so that when dilator D is ina position to extend from distal portion 36 of sheath 20, the hub ofdilator D engages and/or locks with mechanism 46. In this way, sheath 20and dilator D can be moved together, e.g. with one handle or control,without the risk of one moving further or in a different way than theother.

Medial portion 34 is curved in this embodiment, so that there is aconcave side 50 and a convex side 52 on opposite sides of thelongitudinal axis. In the illustrated embodiment, the concave curvatureof side 50 extends around about 20-40 degrees of arc, although it willbe understood that the curvature could extend through greater or lesseramounts of arc depending on the particular use or area of the body inwhich sheath 20 is to be used. The exemplary embodiment can be used inplacing sheath through the right atrial appendage to access thepericardium, as will be explained further below. Medial portion includesinner layer 22 with its constant diameter lumen 24, core coil 28 andouter layer 26. In particular embodiments, the curvature of medialportion 34 is formed and maintained by initially forming or imbuing oneor both of core 28 and outer layer 26 with the curvature. In this way,when sheath 20 is assembled, as by forcing a curved core 28 over innerlayer 22, the curvature of core 28 is imparted to layer 22. Similarly,if outer layer 26 is a heat-settable material, it may be set aftersheath 20 is assembled to the desired curvature, so that outer layer 26forces its set curvature onto core 28 and layer 22.

Distal portion 36 adjoins curved medial portion 34, and in theillustrated embodiment is straight linear and has a joining part 56 thatconnects to medial portion 34, an end 58 with an opening 60 thatcommunicates with lumen 24, and an indented portion 62 (with edges 63 a,63 b) between part 56 and end 58. It has been found preferable tominimize the length from indented portion 62 to the tip of end 58 (i.e.at opening 60), with examples being 6 millimeters or less. Straightdistal portion 36 includes outer layer 26 and inner layer 22, but doesnot include coil core 28, so that distal portion 36 is more flexibleand/or softer than medial portion 34 and proximal portion 32. Joiningpart 56 has an outer diameter (of outer layer 26) that is the same asthe outer diameter of medial portion 34 and proximal portion 32. End 58reduces in outer diameter from an outer diameter adjacent indentedportion 62 that is the same as the outer diameter of part 56, to anouter diameter at opening 60 that is minimally larger than the diameterof lumen 24. In this way, opening 60 has a lip or edge that is about thesame as the outer diameter of a dilator D that passes through opening60, and presents little or no step between dilator D and the outersurface of end 58, thereby reducing or eliminating the risk of trauma totissue as sheath 20 moves (with dilator D) through the tissue. Thereduction in outer diameter may be a result of reducing the thickness ofouter layer 26, the thickness of inner layer 22, or both.

Indented portion 62, as already noted, is between end 58 and part 56,and has an outer diameter that is less than that of part 56, medialportion 34 and proximal portion 32. A balloon 64 is within part or allof portion 62 in the illustrated embodiment, so that when balloon 64 isnot inflated it is at or below the maximum outer diameter of end 58(i.e. the outer diameter of joining part 56, which is the same as theouter diameter of medial portion 34 and proximal portion 32 of sheath20), and fully inside of edges 63 a, 63 b. In this way, when uninflatedballoon 64 does not present a larger profile than the rest of sheath 20.

Balloon 64, in the illustrated embodiment, is a layer of expandablematerial fixed in an airtight fashion to the outer surface of indentedportion 62. Balloon 64 extends around the entire circumference of sheath20, and in particular embodiments has a constant length L as measuredalong the longitudinal axis of sheath 20. Fluid (e.g. air or other gas,or saline or other liquid) is forced between balloon layer 64 and theouter surface of indented portion 62 to expand balloon 64 and a volumeenclosed by balloon layer 64 and the outer surface of indented portion62. Alternatively, balloon 64 may be an annular balloon fixed withinindented portion 62, so that forcing fluid into balloon 64 results inexpansion of balloon 64 and a volume enclosed by balloon 64, but notcontacting indented surface 62. In either case, or with otherconfigurations of balloon 64, a proximal edge 68 of balloon 64 is withinthe straight distal portion 36 of sheath 20, and inflates coaxially withrespect to the longitudinal axis of sheath 20. That is, balloon 64expands all the way around the circumference of indented portion 62.Preferably the expansion is to the same or approximately the same extentat all locations around the circumference, e.g. the expanded extent ofballoon 64 is at least approximately the same distance from thelongitudinal axis of sheath 20 all the way around the outermost diameterof balloon 64. In particular embodiments, the outermost edges of balloon64 in its expanded condition have a diameter that is at least 2 timesthe outer diameter of sheath 20 (e.g. maximum outer diameter of distalsection 36), and preferably at least 3 times that diameter.

In particular embodiments, balloon 64 presents a surface 68 generallyfacing proximally (e.g. toward medial portion 34 and/or proximal portion32 of sheath 20) when balloon is inflated. Surface 68 in the illustratedembodiment has an angle of approximately 90 degrees with respect to thelongitudinal axis of sheath 20, along at least a portion of surface 68,such as the portion closest to the outer surface of sheath 20 in oradjacent to indented portion 62. In other embodiments, the angle ofsurface 68 (or at least the closest portion to the outer surface ofsheath 20) with respect to the longitudinal axis is between or including85 and 90 degrees, between and including 75 and 90 degrees, and/orbetween and including 60 and 90 degrees (e.g. an angle of at least 60degrees with respect to the longitudinal axis of sheath 20. Surface 68,as will be explained further below, is adapted to engage tissue throughwhich sheath 20 extends, to prevent sheath 20 from moving back throughthe tissue. Sheath 20 can be retracted through such tissue when balloon64 is deflated.

One or more markers 69 may be placed at the base of indented portion 62.In the illustrated embodiment, a band of biocompatible metal is placedaround the outside of outer layer 26 of sheath 20 and abutting (e.g.touching) the proximal end of indented portion 62. Such a band isradiopaque and reflects ultrasound. It will be understood that otherembodiments of marker(s) 69 may be of other radiopaque and/or echogenicmaterial, or capable of being imaged via other types of imaging systems.It will also be understood that marker(s) 69 may be at particular pointsrather than formed as a band, or in other formations so as to be easilyseen from a number of directions under imaging. The placement ofmarker(s) 69 is to show at least approximately where surface 68 will bewhen balloon 64 is inflated. Dilator D is preferably more radiopaque orechogenic than sheath 20 (or particularly marker 69) so as to provide acontrast with sheath 20 during imaging. In the illustrated embodiment,one or more marker(s) 69 are also placed at the tip of end 58, adjacentopening 60, so as to be able to show the operator when the tip isthrough the RAA tissue, on entry or on later retraction at the end of aprocedure. Marker(s) 69 are preferably more radiopaque or echogenic thandilator D so that marker(s) 69 can be easily seen when dilator D iswithin and being used with sheath 20.

An inflation channel extends through or along sheath 20 to balloon 64.In a particular embodiment, an inflation lumen 70 is along lumen 24 andextends to an opening 72 in indented portion 62 and under or withinmaterial of balloon 64. Lumen 70 and lumen 24 may be separate lumens insheath 20, as in a multi-lumen catheter, or may be coaxial within sheath20 as in a coaxial catheter. In other embodiments, inflation lumen 70may be along the exterior of sheath 20 or through one or both of layers22, 26. Lumen 70 is connected to a source of fluid and/or pressure (notshown), e.g. a syringe), so that fluid (e.g. air or saline) can beforced into or behind balloon 64 to inflate balloon 64. Such a sourcemay also be used to withdraw fluid or pressure to deflate balloon 64when desired. In particular embodiments, additional lumen(s) andcorresponding communicating opening(s) or port(s) in proximal portion 32and distal portion 36 may be provided for passage of contrast medium,medications, or other fluids. For example, such port(s) or opening(s)for inflation lumen 70 and/or passage of other fluids can be located ator near hub 46 facing in the direction that medial curved portion 34curves toward, i.e. on the side of hub 46 that corresponds or islongitudinally aligned with concave side 50. In such embodiments,opening 72 (and other opening(s) for other fluids) will also be on theside of distal portion 36 that corresponds or is longitudinally alignedwith concave side 50.

Use of sheath 20 will now be described, in the particular context ofplacement through the right atrial appendage (RAA) during placement of abelt or other device around the heart in treating tricuspid valveregurgitation (TR). It will be understood that embodiments of sheath 20could be used in any of a number of internal diagnostic or treatmentprocedures.

With balloon 64 deflated, and therefore within or even with the maximumouter diameter of sheath 20 in distal portion 36, sheath 20 is insertedinto the body. In the embodiment illustrated in FIG. 4, a dilator D isshown so as to make and/or dilate a hole through the RAA, which has aforward surface that corresponds with the tip of end 58 of distalportion 36 of sheath 20. It will be understood that dilator D may be inthe illustrated position with respect to sheath 20 when sheath 20 isinserted into the body, or may be passed through sheath 20 to theillustrated position after sheath 20 is inserted, e.g. just beforemoving sheath 20 through the tissue of the RAA and into the pericardialcavity.

Insertion of sheath 20 may be performed over a previously-placed wire ofa wire guide as is known, e.g. one previously placed through thevasculature, right atrium, and tissue of the right atrial appendage tothe pericardial cavity or space. In a particular embodiment, sheath 20is inserted into the venous vasculature (e.g. into an iliac vein or theinferior vena cava (IVC)). If not initially inserted into the IVC, thensheath 20 is moved to and through the IVC, into the right atrium of theheart and to a location adjacent the RAA. Previously, access to theright atrium has been accomplished from a superior position, such as thejugular vein. However, it has been found that an inferior approach,through the IVC to the right atrium, has significant advantages in termsof patient comfort and care, ease of guidance, movement to and throughthe atrium and the RAA, and passage of treatment devices through sheath20.

With sheath 20 (and dilator D in this embodiment) adjacent the RAA, asseen in FIG. 5, direction of dilator D and sheath 20 through hole H andinto the pericardial cavity PC occurs (FIG. 6-7). Hole H may have beenmade previously, e.g. by a guiding wire such as one along which sheath20 is moved or other tool, or may be made by dilator D or a tool passedalong sheath 20. Sheath 20 with dilator D is moved so that dilator Dengages RAA tissue at hole H, and is moved through the tissue so as todilate hole H. The tissue around hole H engages the outside of dilator Dand slides onto and around distal portion 36 of sheath 20, so thatlittle or no leakage of fluid from the pericardial cavity into the RAAoccurs. It will be understood that dilator D could be extended fromsheath 20 (e.g. leaving sheath 20 stationary) and through the RAAtissue, and then sheath 20 may be advanced over dilator D and throughhole H. In embodiments in which sheath 20 includes marker(s) 69, sheath20 can be imaged (by x-ray, ultrasound, or other imaging system) to seewhere marker(s) 69 are with respect to the RAA tissue through whichsheath 20 extends. When marker(s) 69 are seen to be past or clear of theRAA tissue (i.e. in the pericardial cavity or to the pericardial side ofthe RAA tissue), the operator stops advancing sheath 20.

When sheath 20 is fully advanced, i.e. balloon 64 and/or indentedportion 62 is beyond the pericardial side of the RAA tissue (as may beindicated by marker(s) 69), the operator inflates balloon 64. Inflationshould not occur prior to balloon 64 passing fully through hole H, sothat hole H is not widened, with potential damage to the RAA and othercomplications. As noted above, balloon 64 inflates coaxially, around theentire circumference of sheath 20. When inflated, surface 68 of balloon64 faces hole H and the pericardial side of the RAA tissue. Inflation ofballoon 64 may engage surface 68 with tissue of the RAA around hole Hdirectly, or the operator may need to retract sheath 20 only to thepoint that surface 68 firmly engages the RAA tissue. At this point,balloon 64 acts as an anchor against further retraction of sheath 20.Outer surface 40, preferably of distal portion 36 of sheath 20 adjacentand proximal of indented portion 62, is through and engaging the sidesof hole H, and balloon surface 68 engages the pericardial side of theRAA.

It is noted that the straight, linear nature of distal portion 36 isadvantageous over ends of catheters or other tubes that curve or curl insuch methods. The linear distal portion 36 provides an even surface forballoon 64 to expand coaxially. It will also provide a better, moreflush fit with hole H through the RAA, to minimize or eliminate leakagebetween sheath 20 and the RAA tissue, and an easier placement throughthat tissue. Further, when a curved catheter is deformed to pass throughthe RAA tissue a tendency to revert to the original curved form iscreated, which stress contributes to the potential for retraction. Thatstress is eliminated with the linear, straight section 36 of sheath 20that passes through the RAA tissue.

With sheath 20 anchored against retraction through hole H, by balloon64, dilator D may be retracted through sheath 20. Other tools ortreatment structure may be passed through lumen 24 of sheath 20 and intothe pericardial cavity. In the example of treatment of TR, a belt (notshown) is passed through sheath 20 and maneuvered around the heart sothat the belt engages the atrioventricular (AV) groove. Additionalstructure may tighten the belt and hold it in place as may be desired.

Once the treatment is completed, and any tools or other structure to bewithdrawn from the pericardial cavity and heart tissue has beenretracted through sheath 20, sheath 20 itself is removed. Balloon 64 isdeflated, so that balloon 64 returns into indented portion 62 of sheath20, and preferably within or even with the adjacent outer diameter ofproximal portion 32 of sheath 20. The operator may first move sheath 20forward to disengage balloon surface 68 from the tissue of the RAA, ifdesired or necessary, so as to ensure that deflation of balloon 64 doesnot deleteriously affect the RAA tissue. With balloon 64 deflated,sheath 20 may be pulled back through hole H with no further enlargementof hole H or damage to the surrounding tissue. An appropriate closure orother treatment for hole H may be applied, via sheath 20 or anotherstructure. Once through hole H, sheath 20 is retracted from the bodyalong the path of entry.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly selected embodiments have been shown and described and that allequivalents, changes, and modifications that come within the spirit ofthe disclosures as defined herein or by the following claims are desiredto be protected. It will be understood that features describedparticularly with respect to one or more specific structures orembodiments may be incorporated into or otherwise used with otherstructures or embodiments as disclosed herein.

The following numbered clauses set out specific embodiments that may beuseful in understanding the present invention:

1. An introducer sheath for insertion through the right atrial appendageinto the pericardial cavity, comprising:

an inner lubricious layer defining an internal lumen extending along alongitudinal axis of the sheath from a proximal end to a distal end ofthe sheath;

an outer heat-settable layer surrounding the inner layer and extendingfrom the proximal end to the distal end;

a coil core fixed between the inner layer and the outer layer, the coilcore extending through at least part of a proximal portion of the sheathand at least part of a medial curved portion of the sheath but not intoa linear distal portion of the sheath which includes the distal end;

wherein the linear distal portion has a circumference around thelongitudinal axis, and includes an indented portion around the entirecircumference, the indented portion having proximal and distal edges anouter diameter less than a maximum outer diameter of the linear distalportion, and further comprising a balloon in the indented portion, theballoon having a deflated condition in which the balloon does not extendpast either of the edges or the maximum outer diameter of the lineardistal portion and an inflated condition in which the balloon extendscoaxially past the maximum outer diameter of the linear distal portionaround the circumference of the linear distal portion, and wherein theballoon in the inflated condition has a surface facing proximally thatis angled with respect to the longitudinal axis at an angle between andincluding 60 to 90 degrees.

2. The sheath of clause 1, wherein the internal lumen has a constantinner diameter through the proximal, medial and distal portions of thesheath.3. The sheath of any of clauses 1-2, further comprising at least onemarker that abuts the proximal edge of the indented portion, the markerbeing at least one of radiopaque and echogenic.4. The sheath of any of clauses 1-3, wherein a tip of the linear distalportion has at least one marker that is adjacent a longitudinal openingof the internal lumen, the marker being at least one of radiopaque andechogenic.5. The sheath of any of clauses 3-4, wherein the marker is proximal of aproximal-most part of the balloon.6. The sheath of any of clauses 1-5, further comprising a fluid lumenthat extends to an opening in the indented portion, whereby a fluid maybe forced through to inflate the balloon and may be withdrawn to deflatethe balloon.7. The sheath of any of clauses 1-6, wherein the inner layer is formedof polytetrafluoroethylene (PTFE).8. The sheath of any of clauses 1-7, wherein the outer layer is formedof PEBAX and heat-set to a desired shape following attachment of theinner and outer layers to each other.9. A method of accessing a pericardial cavity of a patient via a rightatrial appendage of the patient with an introducer sheath, comprising:

inserting the introducer sheath into the inferior vena cava of thepatient, the introducer sheath having a curved medial portion and alinear distal portion, the linear distal portion including an indentedportion around the entire circumference and a balloon in a deflatedcondition within the indented portion so that no part of the balloonextends beyond a maximum outer diameter of the linear distal portion oroutside of the indented portion;

moving the introducer sheath to the right atrium of the heart of thepatient to a position adjacent the right atrial appendage;

passing the sheath through the right atrial appendage to the pericardialcavity so that the indented portion is within the pericardial cavity;

inflating the balloon within the pericardial cavity, wherein theinflating does not enlarge a hole through the right atrial appendagethrough which the sheath passes; and

engaging the balloon with tissue of the right atrial appendage thatfaces the pericardial cavity.

10. The method of clause 9, wherein the introducer sheath is theintroducer sheath of claim 1.11. The method of any of clauses 9-10, further comprising imaging thesheath when the sheath extends through the right atrial appendage, andconfirming that a marker abutting a proximal edge of the indentedsection is beyond the tissue of the right atrial appendage beforeperforming the inflating step.12. The method of any of clauses 9-11, wherein a dilator is within andextending from the sheath, and the passing step includes dilating a holethrough the right atrial appendage with the dilator.13. The method of any of clauses 9-12, further comprising passing one ormore devices through the sheath and into the pericardial cavity for usein a treatment procedure after said engaging step, and while the balloonis inflated and engaged with tissue of the right atrial appendage.14. The method of clause 13, wherein the one or more devices includes abelt for placement in the atrioventricular groove as a treatment fortricuspid valve regurgitation.15. The method of any of clauses 9-14, further comprising deflating theballoon so that the balloon collapses to a condition within the indentedportion so that no part of the balloon extends beyond a maximum outerdiameter of the linear distal portion or outside of the indentedportion.16. The method of clause 15, further comprising a disengaging stepbetween the engaging and deflating step, wherein the disengaging stepincludes moving the sheath with respect to the right atrial appendage tomove the balloon away from tissue of the right atrial appendage thatfaces the pericardial cavity.

1-8. (canceled)
 9. A method of accessing a pericardial cavity of apatient via a right atrial appendage of the patient with an introducersheath, comprising: inserting the introducer sheath into the inferiorvena cava of the patient, the introducer sheath having a curved medialportion and a linear distal portion, the linear distal portion includingan indented portion around the entire circumference and a balloon in adeflated condition within the indented portion so that no part of theballoon extends beyond a maximum outer diameter of the linear distalportion or outside of the indented portion; moving the introducer sheathto the right atrium of the heart of the patient to a position adjacentthe right atrial appendage; passing the sheath through the right atrialappendage to the pericardial cavity so that the indented portion iswithin the pericardial cavity; inflating the balloon within thepericardial cavity, wherein the inflating does not enlarge a holethrough the right atrial appendage through which the sheath passes; andengaging the balloon with tissue of the right atrial appendage thatfaces the pericardial cavity.
 10. The method of claim 9, wherein theintroducer sheath is the introducer sheath of claim
 1. 11. The method ofclaim 9, further comprising imaging the sheath when the sheath extendsthrough the right atrial appendage, and confirming that a markerabutting a proximal edge of the indented section is beyond the tissue ofthe right atrial appendage before performing the inflating step.
 12. Themethod of claim 9, wherein a dilator is within and extending from thesheath, and the passing step includes dilating a hole through the rightatrial appendage with the dilator.
 13. The method of claim 9, furthercomprising passing one or more devices through the sheath and into thepericardial cavity for use in a treatment procedure after said engagingstep, and while the balloon is inflated and engaged with tissue of theright atrial appendage.
 14. The method of claim 13, wherein the one ormore devices includes a belt for placement in the atrioventriculargroove as a treatment for tricuspid valve regurgitation.
 15. The methodof claim 9, further comprising deflating the balloon so that the ballooncollapses to a condition within the indented portion so that no part ofthe balloon extends beyond a maximum outer diameter of the linear distalportion or outside of the indented portion.
 16. The method of claim 15,further comprising a disengaging step between the engaging and deflatingstep, wherein the disengaging step includes moving the sheath withrespect to the right atrial appendage to move the balloon away fromtissue of the right atrial appendage that faces the pericardial cavity.17. A method of accessing a pericardial cavity of a patient with anintroducer sheath, comprising: inserting the introducer sheath into theinferior vena cava of the patient, the introducer sheath having aballoon in a deflated condition; moving the introducer sheath into theheart of the patient; passing the sheath through a wall of the heart tothe pericardial cavity so that the balloon is within the pericardialcavity; inflating the balloon within the pericardial cavity; andengaging the balloon with tissue of the wall of the heart that faces thepericardial cavity.
 18. The method of claim 17, wherein the introducersheath has a curved medial portion and a linear distal portion, thelinear distal portion including an indented portion around the entirecircumference and a balloon in a deflated condition within the indentedportion.
 19. The method of claim 17, further comprising passing one ormore devices through the sheath and into the pericardial cavity for usein a treatment procedure after said engaging step, and while the balloonis inflated and engaged with tissue of the wall of the heart.
 20. Themethod of claim 19, wherein the one or more devices includes a belt forplacement in an atrioventricular groove of the heart as a treatment fortricuspid valve regurgitation.
 21. A method of delivering an implant toa pericardial cavity of a patient, comprising: inserting an introducersheath into the inferior vena cava of the patient, the introducer sheathhaving a balloon in a deflated condition, and introducer sheath furtherhaving a lumen extending to an opening at a distal end of the introducersheath; moving the introducer sheath into the heart of the patient;passing the sheath through a wall of the heart to the pericardial cavityso that the balloon is within the pericardial cavity; inflating theballoon within the pericardial cavity; engaging the balloon with tissueof the wall of the heart that faces the pericardial cavity; and passingthe implant through the lumen and out of the opening at the distal endof the introducer sheath.
 22. The method of claim 21, wherein theimplant comprises an annuloplasty belt.
 23. A method of accessing apericardial cavity of a patient with an introducer sheath, comprising:positioning a distal end of the introducer sheath within the heart ofthe patient; passing the distal end of the sheath through a wall of theheart to position the distal end of the sheath and a balloon of theintroducer sheath in the pericardial cavity; inflating the balloonwithin the pericardial cavity; and engaging the inflated balloon withexternal tissue of the wall of the heart that faces the pericardialcavity.
 24. The method of claim 23, wherein said wall of the heart is awall of a right atrial appendage of the heart.
 25. The method of claim24, wherein said positioning includes passing the distal end of thesheath through a vena cava of the patient and into the heart of thepatient.
 26. The method of claim 25, wherein said engaging the inflatedballoon includes contacting said external tissue of the wall of theheart with a surface of the inflated balloon, wherein said surface ofthe inflated balloon extends at an angle between and including about 60to about 90 degrees relative to a longitudinal axis of the introducersheath.
 27. The method of claim 26, wherein the introducer sheath has acurved medial portion and a linear distal portion, the linear distalportion including an indented portion around the entire circumferenceand a balloon within the indented portion, wherein the balloon is in adeflated condition during said passing step.
 28. The method of claim 25,also comprising, after said engaging, passing an annuloplasty beltthrough a lumen of the introducer sheath and out of an opening at thedistal end of the introducer sheath.